Fix PseudoTcp to handle incoming packets with invalid SEQ field
Fix PseudoTcp to handle incoming packets with invalid SEQ field

Previously PseudoTcp::process() didn't handle the case when the peer
sends a packet that's outside of the receive window, which was causing
DCHECK failures in the fuzzer.

BUG=681849

Review-Url: https://codereview.webrtc.org/2640173002
Cr-Original-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#16169}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: d74886350e432547e7a70095170fe1a9a0dab0c8

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